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Biomedical subjects

J H Scurr

Publications and source records attributed to J H Scurr.

At least 19 recordsLinked to original sources
PubMed1995

Effects of compression and type of bed surface on the microcirculation of the heel.

OBJECTIVE: To assess the effects of compression on the skin microcirculation of the heel using laser Doppler fluxmetry. DESIGN: Parallel groups comparing patients with control groups. SETTING: Department of Surgery, University College London Medical School, London. SUBJECTS AND MATERIALS: Ten patients at risk of developing pressure ulceration, 10 age- and sex-matched healthy subjects and 10 young, healthy volunteers. An acrylic indenter with a slot to accommodate a laser Doppler probe was used to apply compression to the heel region. A pressure sensor was used to measure the applied compression. OUTCOME MEASURES: The resting laser Doppler flux was measured with the subject lying supine. Compression forces were then applied in increments from 50 g to 1500 g and the corresponding interface pressure (IP) and laser Doppler flux (LDF) recorded. The IP and LDF were also measured from the heel while the subject was lying on a low air-loss system and then on an NHS conventional hospital bed. RESULTS: The resting LDF is lower in the patient group compared to the control groups (p < 0.05). Compression of the heel caused a progressive decrease in LDF in all groups. Compression greater than 50 mmHg as well as lying on an NHS bed reduced the LDF signal to a minimal value (biological zero). On the low air-loss system, the median LDF was 17% of the resting value in the age-matched control group and 32% in the patient group. CONCLUSIONS: The results indicate that the heel microcirculation is vulnerable to compression. The low air-loss system maintained the IP sufficiently low to prevent complete cessation of the heel microcirculation.

Adult↗
PubMed1992

Mechanism of action of external compression on venous function.

Compression stockings and bandages have been shown to improve venous haemodynamics and may act by reducing venous reflux. The aim of this study was to assess the mechanism of action of compression therapy on venous function and to determine whether such treatment may correct valvular incompetence. Both lower limbs of 36 patients (median age 59 (interquartile range 45-65) years) were assessed by duplex ultrasonographic scanning. There were 17 limbs with popliteal vein reflux, 19 with long saphenous vein (LSV) reflux and 21 with short saphenous vein (SSV) reflux. A water-filled adjustable pressure cuff was applied around the knee and inflated gradually, while continuously assessing the veins for reflux using ultrasonographic imaging. The external pressure applied by the cuff was noted when reflux was abolished or when the vein was completely occluded. In four (24 per cent) of 17 popliteal veins, eight (42 per cent) of 19 LSVs and three (14 per cent) of 21 SSVs reflux was abolished before occlusion of the vein. The cuff pressures required to achieve restoration of valvular function were significantly lower than those required to occlude the veins. It is possible, in some refluxing veins, to correct valvular dysfunction by external compression therapy. Coaptation of valvular cuffs to restore valvular competence may be the mechanism of action of compression therapy in venous disease.

Aged↗
PubMed1992

Assessment of stripping the long saphenous vein in the treatment of primary varicose veins.

Stripping of the long saphenous vein (LSV) may prevent recurrence of varices, although this has not been demonstrated using objective criteria. The aim of this study was to determine whether the addition of LSV stripping, from groin to upper calf, to saphenofemoral junction (SFJ) ligation prevents residual reflux, and whether LSV stripping to the upper calf results in greater neurological complications. Sixty-nine patients with primary varicose veins, LSV reflux and SFJ incompetence, confirmed by duplex ultrasonography and photoplethysmography, were studied. A total of 105 limbs were treated by SFJ ligation and avulsion of varices; patients were randomized to undergo stripping of the LSV to the upper calf (n = 49) or no additional treatment (n = 56). Three months after surgery all patients were examined clinically, by duplex ultrasonography and by photoplethysmographic tests of venous function, to establish the extent of persisting varices. Fewer persisting incompetent LSVs in the calf were found when the LSV was stripped (n = 9) than after SFJ ligation alone (n = 25) (P < 0.01). Photoplethysmographic refilling times were improved to a similar extent in both groups after surgery but were lower in those who had residual LSV reflux (P < 0.05). Six limbs developed paraesthesia in the distribution of the saphenous nerve: two in the group that were stripped and four in those that were not. These data suggest that LSV reflux is more completely abolished by combining LSV stripping with SFJ ligation; stripping the LSV to the upper calf does not result in a higher incidence of injury to the saphenous nerve.

Aged↗
PubMed1992

Family history and risk of breast cancer.

The risk of breast cancer in first degree relatives of patients with breast cancer can be derived from family history and is dependent upon the age at diagnosis in the index patient. For the relatives of index patients older than 55, the relative risk is 1.57, if less than 55 the relative risk is 2.29, and 3.85 if less than 45 (95% confidence limits 0.83 to 2.68, 1.18 to 4.01, and 1.67 to 3.85, respectively). First degree relatives of patients with bilateral breast cancer have a 6.43-fold increase in risk (95% confidence limits 1.32 to 18.77). The genetic contribution to overall lifetime liability to breast cancer in the relatives declines rapidly with increasing age of onset of breast cancer in the index patient from 37% at 20 years to 8% by 45 years. This information can be used in clinical practice for counselling and the establishment of screening programmes.

Adult↗
PubMed1992

Leg ulceration in venous disease.

We have given a brief summary of the scale of the problem caused by venous ulceration in the UK, and have then reviewed the various theories of causation, including a historical survey, and presented the evidence for and against the two main current theories of fibrin cuffs and white cell trapping. We also outline previous hypotheses of the aetiology of venous ulceration, including arteriovenous microanastomoses, stasis and oedema. The contribution of superficial venous incompetence in the pathogenesis of ulceration is also examined.

Arteriovenous Fistula↗
PubMed1992

Photoplethysmography: a valuable noninvasive tool in the assessment of venous dysfunction?

We have investigated the photoplethysmography findings in 152 patients admitted to the Middlesex Hospital Vascular Laboratory with suspected lower limb venous disease, and we compared the results obtained with patient grouping using clinical criteria and the presence of reflux on color duplex scanning. All photoplethysmography traces were normalized with use of computer software to enable direct comparison between the traces. The parameters investigated were the 95% and 50% refilling times and the initial gradient of the refilling curve. Receiver operating characteristic curves were constructed to determine which parameter was the most useful predictor of disease and to identify which value within each observation gave the greatest sensitivity and specificity. We found a large overlap between interquartile values for all three parameters, with limbs grouped both clinically and by duplex scanning, making differentiation between normal and abnormal limbs difficult on the basis of photoplethysmography traces alone. We found that a 95% refilling time of less than 15 seconds indicated venous dysfunction with the greatest sensitivity and specificity and suggest that this value is most useful. Photoplethysmography readings are reproducible, noninvasive, and correlate well with the presence of clinical disease, and photoplethysmography remains useful in the assessment of venous dysfunction.

Adult↗
PubMed1992

Medial calf perforators in venous disease: the significance of outward flow.

The role of medial calf perforators in the initiation or promotion of venous disease is incompletely understood. The purpose of this study was to define the direction of blood flow in the perforating vein of the calf in normal limbs and in those limbs of patients with venous disease under defined laboratory conditions. Both lower limbs of 57 patients, (32 women and 25 men, median age, 56 years; range, 40 to 62 years) were examined by duplex ultrasonography. In 10 patients no clinical or duplex evidence existed of venous disease. In 60 legs we found evidence of superficial venous insufficiency, complicated by lipodermatosclerosis in 29. In 15 limbs we found deep venous insufficiency. Finally, in 19 limbs no evidence existed of venous disease, but venous reflux was present in the contralateral limb. The direction of blood flow in the medial calf perforators was assessed during compression of the foot and calf, by a cuff that inflated to 60 mm Hg. Blood flow was also assessed during deflation of the cuff. We found that the direction of blood flow within medial calf perforators can be both inward or outward, even in limbs without evidence of venous disease. Outward flow could be demonstrated in 21% of perforators in normal limbs. Flow on release of distal compression occurred in 33% to 44% of perforators in limbs with evidence of venous disease but in none of the perforators in limbs without evidence of venous disease. We found that flow, during the relaxation phase, within medial calf perforators was associated with venous disease elsewhere in the limb.

Adult↗
PubMed1992

Vasomotion in the leg skin of patients with chronic venous insufficiency.

The characteristics of vasomotor activity in patients with lipodermatosclerosis (LDS) were studied using Laser Doppler fluxmetry and frequency analysis. Laser Doppler flux in the skin was recorded in the goiter region in 17 patients with LDS due to venous disease and in 16 normal control subjects. The Laser Doppler signals were analysed to give mean levels of flux and the frequency and amplitude of vasomotion were found using a fast Fourier transform (FFT). The results show significantly greater basal flow (p less than .001), and vasomotor frequency (p less than .001) and amplitude (p less than .001) in venous disease. The altered vasomotor activity is not due simply to the increased flow in LDS since increasing the flow in normal skin using the vasodilator pilocarpine does not produce as noticeable a difference.

Adult↗
PubMed1991

Histological study of white blood cells and their association with lipodermatosclerosis and venous ulceration.

The number of white blood cells per mm2 has been determined in serial histological slides taken from punch biopsies of skin from the goiter region in patients with varicose veins. In eight patients the varicose veins were complicated by lipodermatosclerosis of the skin, and in a further six there was a history of ulceration. In uncomplicated varicose veins there was a median of 6 white blood cells per mm2, in patients with lipodermatosclerosis there were 45 white blood cells per mm2, and where there was a history of ulceration, 217 white blood cells per mm2. No change in white blood cell content was observed after the venous pressure was raised for 30 min by sitting the patient with the lower limb dependent. White blood cell infiltration of the skin is associated with lipodermatosclerotic changes caused by venous insufficiency.

Humans↗
PubMed1991

Near-infrared spectroscopy in peripheral vascular disease.

Near-infrared spectroscopy has been performed on the calf muscles of 38 subjects, 21 normal controls without vascular disease and 17 patients with peripheral vascular disease. Oxygen consumption was measured in the calf by calculating the rate of conversion of oxyhaemoglobin to deoxyhaemoglobin during a period of tourniquet-induced ischaemia. Postischaemic reoxygenation was also measured. Median oxygen consumption in patients with peripheral vascular disease was 0.10 ml 100 g tissue-1 min-1, while in the control group it was 0.20 ml 100 g tissue-1 min-1 (P less than 0.03, Mann-Whitney U test). The median time taken to reach maximum oxyhaemoglobin levels after ischaemia was 40 s in patients with peripheral vascular disease and 20 s in controls (P less than 0.02). The results indicate that oxygen consumption is reduced in peripheral vascular disease. Near infrared spectroscopy is a non-invasive method for assessing metabolic improvement resulting from surgical or pharmacological treatment.

Adult↗
PubMed1991

Vasodilatory capacity of the skin in venous disease and its relationship to transcutaneous oxygen tension.

Low transcutaneous oxygen tension (Ptc,O2) values in the supramalleolar skin of patients with venous disease are often reported. This measurement involves heating the skin to 43 degrees C to cause maximum vasodilatation and is valid only if liposclerotic and normal skin can vasodilate to the same degree. Forty-four limbs were studied, 15 with lipodermatosclerosis (LDS), 14 with uncomplicated varicose veins, and 15 controls. A Ptc,O2 electrode was modified to incorporate a laser Doppler probe. Laser Doppler flux was measured in the supramalleolar skin before and after local heating to 43 degrees C and the relative increase in flux was measured. The Ptc,O2 was then measured at the same site and on the chest. Vasodilatory capacity was expressed as the ratio of peak:basal laser Doppler flow, and the Ptc,O2 was expressed as a leg:chest ratio. Median laser Doppler flow was higher in limbs with LDS (median 67 mV) than in normal limbs (median 40 mV) (P less than 0.03). Ptc,O2 was higher in control limbs (median ratio 0.94) than in limbs with LDS (median 0.53) (P less than 0.006). The microcirculation in LDS had less capacity to vasodilate after heating (median factor of increase 5.4) than normal skin (median factor of increase 12.3) (P less than 0.001). A simple regression analysis was performed on all pairs of data, and revealed a correlation between Ptc,O2 and vasodilatory capacity (r = 0.524, P less than 0.001). The results indicate that low Ptc,O2 levels in venous disease reflect an inability of the microcirculation to increase its flow in response to local heating; inferences about the oxygen content of liposclerotic skin at normal temperatures cannot be drawn using this technique.

Adult↗
PubMed1991

Deep vein thrombosis: effect of graduated compression stockings on distension of the deep veins of the calf.

The mechanisms by which graduated compression stockings prevent deep vein thrombosis are not completely understood. Recent work has suggested that venous distension plays a role in initiating the process. Our previous work has shown that the deep veins of the lower limb distend in patients undergoing surgical procedures. We have investigated 40 patients receiving surgical treatment on the abdomen or neck. A medial gastrocnemius vein was studied using ultrasound imaging during the operations. In half the patients a graduated compression anti-embolism stocking was applied to the limb under study at the start of the operation, immediately after initial measurements of vein diameter. The median vein diameter in both groups was the same at the start of the operative procedures (control, 2.6 mm, interquartile range 2.1-3.3 mm; stocking, 2.6 mm, interquartile range 2.1-3.7 mm). After application of a stocking the median diameter in this group fell to 1.6 mm (interquartile range 1.3-2.8 mm) and then decreased slightly at the end of the operation. In the control group the vein diameter increased to 2.9 mm (interquartile range 2.3-4.0 mm) during the operative procedure.

Abdomen↗
PubMed1991

Objective assessment of high ligation without stripping the long saphenous vein.

Non-invasive methods of venous assessment were used to assess the procedure of high ligation plus multiple avulsion of varicosities for the treatment of varicose veins in 54 limbs. Duplex scanning before operation confirmed saphenofemoral incompetence and excluded short saphenous incompetence. After operation it revealed that in two limbs the saphenofemoral junction was still patent and incompetent. In the 52 limbs in which the junction had been ligated there was persistent reflux down the long saphenous vein in 24 cases. In only two limbs was this attributable to mid-thigh perforating veins. Photoplethysmography was also performed before and after operation and the venous refilling time measured. Improvement in refilling time produced by application of above knee tourniquets before operation was measured (predicted improvement) and the change in refilling time after operation was also recorded (observed improvement). There was a statistically significant correlation between observed improvement and predicted improvement in refilling times in the limbs with no reflux in the long saphenous vein after operation (Pearson's correlation coefficient, r = 0.6, P less than 0.001). There was no correlation between predicted and observed refilling times in the limbs with persisting reflux in the long saphenous vein after operation. In conclusion, this operation fails to control functionally significant reflux within the long saphenous vein in a high proportion of cases.

Humans↗
PubMed1991

The pathogenesis of skin damage in venous disease: a review.

Venous ulceration remains a major cause of morbidity. Treatment has not improved significantly in recent years, possibly because our understanding of the pathophysiological mechanisms at work is still incomplete. We review the principal abnormalities found in the macro- and microcirculation in this condition and discuss the various theories put forward to explain the mechanism by which skin damage occurs.

Fibrin↗
PubMed1991

Selection of amputation level: a review.

Preservation of the knee joint in a patient undergoing lower limb amputation for critical ischaemia is associated with improved postoperative rehabilitation and mobility. Yet, for most surgeons the below-knee to above-knee amputation ratio remains less than one. Poor wound healing and a high reamputation rate for below knee stumps are important factors mitigating against below-knee amputations. Many tests (Doppler indices, segmental pressures, skin blood flow, skin perfusion pressure, TcpO2, thermography) have been described to predict the likelihood of successful healing of an amputation stump but none appears to have gained widespread acceptance. Clinical judgement alone is insufficient to predict the success or failure of an amputation stump. In this review, we have looked at the evidence in support of these tests, particularly those routinely available to most surgeons.

Amputation, Surgical↗